x-coordinate of the vertex= -b/(2a). "b" is the second coefficient and "a" is the first. Once you find this, plug that in for x and solve for y. The vertex will be this point, (x,y).
y=4x^2+12x-11. x-coordinate= -b/(2a)= -12/(2*4)= -12/8. Simplied: -3/2. Plug in x= -3/2 and solve for y.
y=4(-3/2)^2+12(-3.2)-11. ----> y= 4(9/4)+12(-3/2)-11. ----> y= 9-18-11 -----> y=-20
VERTEX: Ans. (-3/2, -20)
POINT OF SYMMETRY: This is either the same thing as the vertex, or if you needed the AXIS OF SYMMETRY, that would be x= -3/2 (a vertical line going through the vertex, dividing the parabola symmetrically in half).
Y-INTERCEPT: This is easy when quadratics are i standard form (not vertex or factored form). You plug in x=0 and solve for y. This is easier in standard form like how the quation was given above, because plugging in x=0 gets rid of any term except the last term. Thus, the y-coordinate is equal to the last term. The answer is to be written as a point: (0, -11).
Good luck and I hope this helps you